1. Field of the Invention
The present invention relates to a pen-based computer system and more particularly to a pen-based wireless interface device that can emulate a standard mouse function with a passive stylus which generates a plurality of mouse data packets for each pen up event to prevent maloperation of the system in the event the data packet for the pen up event is lost or garbled.
2. Description of the Prior Art
Pen-based portable personal computer systems are generally known in the art. Such systems typically include a digitizer panel and a pen controller and utilize a stylus as an input device. The pen controller normally generates a series of interrupts and, in turn, a series of packets whenever the stylus touches or is lifted from the digitizer panel. The x-y coordinates of each pen down event are generated as a series of four 8-bit packets (p1, p2, p3, p4). Pen up data is generated as a single packet p5. In certain conditions, the interrupts are disabled in order to enable the pen packets to be processed. During the time when the interrupts are disabled, the x-y coordinate packets (p1, p2, p3, p4), as well as the pen up packet p5, are not processed and thus can become garbled or lost. Since mouse emulation is based on both pen-down and pen-up events, lost pen-up packets p5 can result in the mouse emulation being hampered, possibly resulting in the system being stuck in the state preceding the pen-up event.